The Life Methanic: Microbial Activity in the Deep Ocean Methanosphere of the Southern California Borderland

Abstract

The deep ocean methanosphere is defined by the microbial communities that cycle methane, the animals that directly consume or form symbioses with methane-consuming microbes, and the transitional animal communities that gain energy indirectly from methane and/or take advantage of the methane-derived authigenic carbonate. Our research seeks to redefine our understanding of the fate and footprint of methane on Pacific continental margins. By applying molecular, isotopic, geochemical, and radiotracer tools to the seep microbes and fauna we hope to better understand the contribution of methane to deep-sea diversity and ecosystem function. During the 2023 expedition AT50-12 with the RV Atlantis and the submersible Alvin we explored a set of methane seeps located in the Southern California Borderland. Samples were taken from seep carbonates, sediments, and the water column surrounding methane vents to study microbial methanotrophic activity and its relevance for methane removal, habitat engineering, and primary productivity. This poster will provide a first glance into new datasets on methanotrophy generated during the expedition and into the heterogeneity of deep ocean methane seeps off the coast of southern California.